Recently, in order to prevent global warming, it is desired to reduce emissions of greenhouse gases such as carbon dioxide and technologies are being developed for capturing carbon dioxide from combustion exhaust gas emitted from an oxyfuel combustion boiler for a storage process in ocean or in the underground formation.
Such an oxyfuel combustion boiler includes an oxygen introduction line which introduces oxygen to an atmosphere supply line connected to a wind box on an input side of a boiler body, and a recirculation gas line branched from an exhaust gas line connected to an output side of the boiler body and connected to the atmosphere supply line. At a start-up, the air is introduced from the atmosphere supply line to the boiler body to burn fuel. After the completion of the start-up, dampers or the like arranged in the lines are switched to circulate an exhaust gas emitted from the boiler body through the recirculation gas line or the like to the boiler body; oxygen is introduced from the oxygen introduction line to the boiler body to perform the oxyfuel combustion of the fuel while constraining the lowering of oxygen concentration due to the recirculation gas to increase the carbon dioxide concentration in the exhaust gas and capture carbon dioxide from a portion of the exhaust gas.
Such technique concerning a method and an apparatus of controlling oxygen supply for a boiler is disclosed, for example, in Patent Literature 1.
[Patent Literature 1] JP 2001-336736A